Investigation into possible presence of immunogical reactivity in colon tumor bearing rats. These studies are based on the observation that a long latent period is required prior to the appearance of a palpable subcutaneous tumor. It is hypothesized that it is in this interval that the host's immune reactivity peaks. Protocol I: Five animal groups to be inoculated with equal number of viable cells subcutaneously. At a predetermined time during latent period various cellular components are to be transferred to designed groups. One of the groups will serve as controls. This experiment may serve to detect the presence of some degree of immune reactivity to the tumor either in the form of antibody or cell mediated immunity. If immune reactivity is present, the transfer of putative immune serum or cells might result in either the extension of the latent period or suppression of tumor growth. Protocol II: Designed to determine whether latent period is a function of the immune response using physiological parameters. The effects of thymectomy and antilymphocytic serum alone and splenectomy alone are to be observed. Furthermore, we intend to provide interested investigators with this tumor cell line, complete observations relating to tumor biology as outlined in progress report recently submitted. Duplicates of progress report are appended.